I analysed all of Mark Niemiec's syntheses in the zip file on the 16 bit SL page. Now there are just 12 SLs in my lists without synthesis. I don't think any of them have explicit synthesis on Mark's website except for 16.126 which I was too lazy to include because it uses quite a number of *WSS.

Now 249 16-bit SLs have synthesis in greater than 15 gliders in my list. I think about 50 of them have no appearance on Catagolue. Here is the updated list sorted by Catagolue frequency:

I pushed an update with the recent syntheses. Also I added Bob's 3G tail adder as a component and worked out how to make 16.1970 from a 15-bit still life. The 3G carrier to long long snake was worked out by me, mimicking a 2G version that does not work in this scenario. I guess that something equivalent or possibly identical was already known. (EDIT: prepended a 8G synthesis of the 15-bitter)